利用砂梨多酚氧化酶减少夏秋红茶苦涩味研究

Bitterness and Astringency in Summer and Autumn Black Tea Decreased by Exogenous Polyphenol Oxidase

以夏秋茶鲜叶为原料,在改善红茶加工工艺的基础上,利用添加砂梨多酚氧化酶来减少茶叶的苦涩味,从而提高夏秋红茶的品质。结果表明,在环境温度35℃、空气相对湿度90%、光照度20 000 lx条件下,鲜叶经日光萎凋15～20 min后再经过18 h的室内萎凋,采用2次揉捻共1 h,在30℃、相对空气湿度95%的恒温恒湿条件下发酵(3～6 h),随着发酵时间的延长,茶叶的感官品质明显提高;砂梨多酚氧化酶可以促进红茶发酵,粗酶液添加量与揉捻叶重量比例在0～10%范围内,随着比例的升高,茶叶感官的内质得分明显上升(r=0.937 5),红茶中苦涩味物质显著减少,同时甜醇类物质显著增加,其中黄酮类物质含量下降了6.8%,茶多酚含量增加了4.2%,可溶性糖含量增加了34.0%。

Using the tea [Camellia sinensis(L.) O.Kuntze] leaves harvested in summer and autumn,based on improving the processing techniques of black tea,exogenous polyphenol oxidase of Pyrus pyrifolia(Burm.f.) Nakaito was applied to decrease the bitterness and astringency of black tea to enhance its quality and improve the utilization of leaves.Results showed that the sensory quality improved significantly with the prolonging of fermentation time under the following conditions,fresh leaves withering by sunlight for 15～20 min at the environment temperature of 35 ℃,RH 90%,intensity of illumination 20 000 lx,then withering for 18 h indoor,tea-rolling twice for a total of 1 h and then fermenting for 3～6 h at the constant temperature of 30 ℃ and RH 95%.As the mass ratio of crude enzyme to rolling leaves ranged from 0 to 10%,the sensory scores increased significantly(r=0.937 5) with the increasing of the ratio,the astringency and bitterness attenuated significantly while sweetness and mellowness increased,as flavonoids decreased by 6.8%,tea polyphenols increased by 4.2%,and soluble sugar increased by 34.0%.Therefore,the quality of summer and autumn black tea got considerable improvement under the techniques.